1. Technical Field
The present disclosure relates to a technique for performing mutual authentication between controllers and devices connected to a network and sharing a group key among the controllers and the devices.
2. Description of the Related Art
Recently, services that utilize various kinds of history information collected to a cloud server from devices, such as home appliances, AV (Audio/Visual) devices, and residential facility devices having a network connection function (hereinafter, simply referred to as “devices”), have been expected.
Such services are conceivably implemented such that a device (hereinafter, referred to as a “controller”.) for controlling devices is installed in a home and the controller relays communications between the devices and the cloud server. In such a case, it is required to prevent spoofing by an unauthorized device and information leakage due to eavesdropping of communication content for connections between the controller and the devices.
As a countermeasure against spoofing by an unauthorized device, authentication is performed between a controller and a device by using PKI (Public Key Infrastructure), for example. In addition, as a countermeasure against information leakage, an authenticated controller and an authenticated device share a key for use in encrypted communication and perform encrypted communication, for example (see, for example, Federal Information Processing Standards Publication (FIPS PUB) 186-4: Digital Signature Standard (DSS), National Institute of Standards and Technology (NIST), July 2013 and NIST Special Publication 800-56A Revision 2: Recommendation for Pair-Wise Key Establishment Schemes Using Discrete Logarithm Cryptography, National Institute of Standards and Technology (NIST), May 2013).
In the case where there are a plurality of devices connected to a controller, if the controller and the plurality of devices share a single key (hereinafter, referred to as a “group key”.) for encrypted communication (see, for example, Japanese Patent No. 4576997), encryption can be applied to simultaneous broadcast transmission (multicast communication) in which the controller simultaneously transmits the same information to the devices.